Supervision and control points and measures for la

2022-08-02
  • Detail

Key points and measures for supervision and control of conduit and trunking laying and wiring

(I) prior supervision and control of construction quality

1 Materials entering the site shall be provided with batch inspection certificates, which can only be used in the construction if they meet the provisions of relevant technical standards

2. Appearance inspection: the steel conduit is free of flattening, the inner wall is smooth, the non galvanized steel conduit is free of serious corrosion, and the paint delivered according to the manufacturing standard is complete; Galvanized steel conduit shall have complete coating and no rust spots on the surface; Insulating conduits and accessories shall not be broken, and the surface shall be provided with flame retardant marks and manufacturer's marks

3. The pipe diameter, wall thickness and evenness of the conduit shall be sampled and tested on site according to the manufacturer's standards. If there is any objection to the flame retardant performance of insulated conduits and accessories, they shall be sampled by batch and sent to a qualified laboratory for testing

4. Installation electricians, welders, hoisting workers and electrical commissioning personnel shall work with certificates according to relevant requirements

5. Various measuring instruments used for installation and commissioning shall be verified to be qualified and within the period of validity when used

6. The laying of wire conduit, cable conduit and trunking shall be carried out according to the following procedures:

(1) except that the inner and outer walls of non galvanized steel conduit into concrete shall be subject to anti-corrosion treatment, the inner and outer walls of non galvanized steel conduit in other places shall be subject to anti-corrosion treatment, and the piping can only be carried out after inspection and confirmation

(2) the route, groove depth, width and cushion treatment of outdoor directly buried conduit can be buried only after inspection and confirmation

(3) in the high-end aluminum green lightweight market, the cast-in-place concrete shall be equipped with pipes bravely before the bottom reinforcement is bound, and the upper reinforcement is laid before it is bound, and it shall be checked and confirmed before the upper reinforcement is bound and the concrete is poured

(4) the reinforcement sheets in the cast-in-place concrete wall are bound, and the positions of doors and windows have been set out. After inspection and confirmation, pipes can be arranged in the wall

(5) the junction box and conduit of concealed works can be concealed only after they pass the inspection before concealment

(6) the conduit sleeve, embedded parts, supports, etc. of the exposed piping at the beam, plate, column and other parts shall be inspected to be qualified before piping

(7) the light position and electrical appliance position on the ceiling shall be set out first, and the piping in the ceiling can only be carried out after consultation with the civil engineering and professional construction units

(8) the trunking and trough plate can be laid only after the spraying, painting or wallpaper of the ceiling and wall are basically completed

(II) supervision control in construction quality matters

1 Laying of wire conduit, cable conduit and trunking

(1) general provisions

① for wire protection pipes laid in dusty or humid places, the pipe orifice and its connection shall be sealed

② when the line is concealed, the wire protection pipe should be laid along the nearest route and reduce bending. The distance between the wire protection pipe buried in buildings and structures and the surface of buildings and structures should not be less than 15mm

③ the wire protection pipes entering the floor type distribution box shall be arranged neatly, and the pipe orifice shall be 50~80mm higher than the foundation surface of the distribution box

④ the wire protection pipe should not pass through the foundation of equipment or buildings and structures; When it is necessary to pass through, protective measures shall be taken

⑤ there shall be no creases, depressions and cracks at the bending of the wire protection tube, and the bending degree shall not be greater than 10% of the outer diameter of the tube

⑥ the bending radius of the wire protection tube shall comply with the following provisions:

1) when the line is exposed, the bending radius shall not be less than 6 times of the outer diameter of the tube; When there is only one bend between two junction boxes, the bending radius shall not be less than 4 times of the outer diameter of the pipe

2) when the pipeline is concealed, the bending radius shall not be less than 6 times of the outer diameter of the pipe; When buried underground or in concrete, the bending radius shall not be less than 10 times of the outer diameter of the pipe

⑦ in case of one of the following situations, the junction box or pull box shall be laid in the middle, and the position of the junction box or pull box shall be convenient for threading:

1) no bending shall be allowed for every 30m of pipe length

2) there is one bend for every 20m of pipe length

3) there are two bends when the pipe length exceeds 15m

4) there are three bends for every 8m of pipe length

⑧ in case of one of the following conditions for the vertically laid wire protection pipe, the pull box for fixing the wire shall be laid:

1) the cross-sectional area of the wire in the pipe is 50 mm2 or less, and the length is more than 30 m

2) the cross-sectional area of the conductor in the pipe is 70~90 ㎜ 2, and the length exceeds 20 meters every time

3) the sectional area of the conductor in the pipe is 120~240 ㎜ 2, and the length exceeds 18 M

⑨ the allowable deviation for horizontal or vertical installation of exposed distribution line protection pipe laid horizontally or vertically shall be 1.5 ‰, and the deviation of the whole length shall not be greater than 1/2 of the pipe inner diameter

⑩ in TN-S and TN-C-S systems, when metal wire protection tube, metal box (box) and plastic wire 3 In the process of transportation, when the protective tube and plastic box (box) are mixed, the metal wire protective tube and metal box (box) must have a reliable electrical connection with the protective wire (PE wire)

(2) steel pipe laying

① thick wall steel pipe or liquid proof flexible metal wire protection pipe shall be used in wet places and wire protection pipes directly buried underground; Thin wall steel pipe or flexible metal wire protection pipe shall be used for wire protection pipe in dry places

② both the inner and outer walls of steel pipes shall be subject to anti-corrosion treatment. When buried in concrete, the outer wall of steel pipes may not be subject to anti-corrosion treatment; The outer wall of the steel pipe buried in the soil layer shall be coated with two layers of asphalt; When galvanized steel pipes are used, the zinc coating peels off the anticorrosive paint. If there are special requirements in the design, anti-corrosion treatment shall be carried out according to the design provisions

③ the steel pipe shall be free of flattening and cracks. There shall be no iron filings and burrs in the pipe. The cut-off port shall be flat and the pipe orifice shall be smooth

④ pipe connection shall meet the following requirements:

1) when threaded connection is adopted, the length of pipe end thread shall not be less than 1/2 of the length of pipe head; After connection, 2 ~ 3 threads should be exposed. The thread surface shall be smooth without defects

2) when the casing is used for connection, the length of the casing should be 1.5 ~ 3 times of the outer diameter, and the butt joint of the pipe should be located in the center of the casing. When the casing is connected by welding, the weld shall be firm and tight; Use set screws for connection, and the screws shall be tightened; In places with vibration, anti loosening measures shall be taken for set screws

3) galvanized steel pipes and thin-walled steel pipes shall be connected by threaded connection or casing set screws, and fusion welding shall not be used

4) the inner surface of the pipe at the steel pipe connection shall be flat and smooth

⑤ the connection between the steel pipe and the box (box) or equipment shall meet the following requirements:

1) the concealed black steel pipe can be connected with the box (box) by welding when the sampling speed is very low, the pipe orifice should be 3 ~ 5mm higher than the inner wall of the box (box), and the anti-corrosion paint should be applied after welding; The connection between exposed and concealed galvanized steel pipes and boxes (boxes) shall be fixed with lock nuts or retainer caps. The pipe end thread fixed with the lock nut should expose 2 ~ 3 threads of the lock nut

2) when the steel pipe is directly connected with the equipment, the pipe shall be laid into the junction box of the equipment

3) when the steel pipe is connected with the equipment, for indoor dry places, the end of the steel pipe should be added with a wire protection hose or a flexible metal wire protection pipe, which should be led into the junction box of the equipment, and the pipe orifice of the steel pipe should be wrapped tightly; For outdoor or indoor wet places, a waterproof elbow shall be added at the end of the steel pipe, and a protective hose shall be added to the conductor, which shall be bent into a dripping arc before being introduced into the junction box of the equipment

4) the distance between the steel pipe orifice connected to the equipment and the ground should be greater than 200mm

⑥ the grounding connection of steel pipe shall meet the following requirements:

1) when the black steel pipe is connected by thread, the two ends of the connection shall be welded with jumper grounding wire or connected by special grounding card

2) the jumper grounding wire of galvanized steel pipe or flexible metal wire protection pipe should be jumper connected with special grounding card instead of fusion welding

⑦ junction box shall be set at the position where the electricity is installed

align the pointer to the zero point ⑧ the exposed steel pipes shall be arranged neatly, the spacing between fixed points shall be uniform, and the maximum distance between steel pipe clamps shall meet relevant requirements; The distance between the pipe clamp and the terminal, the midpoint of the elbow, and the edge of the electrical appliance or box (box) should be 150 ~ 500mm

(3) metal hose laying

① metal hose or flexible metal wire protection pipe should be used as wire protection pipe between steel pipe and electrical equipment and appliances; The length of metal hose shall not be greater than 2m

② the metal hose shall be laid in a dry place that is not easy to be damaged by machinery, and shall not be directly buried underground or in concrete. When metal hoses are used in wet and other special places, liquid proof metal hoses with non-metal sheaths and supporting connecting devices shall be used, and the sheaths shall be subject to flame retardant treatment

③ the metal hose shall not be degummed or loosened, and there shall be no joint in the middle; When connecting with equipment and appliances, special joints shall be used, and the joints shall be sealed reliably; The connection of liquid proof metal hose shall be well sealed

④ the installation of metal hose shall meet the following requirements:

1) the bending radius shall not be less than 6 times of the outer diameter of the hose

2) the distance between fixed points shall not be greater than 1 m, and the distance between pipe clamp and the midpoint of terminal and elbow shall be 300 mm

3) the fixed pipe clamp at the end of the metal hose connected to the embedded lamp or similar appliance should be installed at 1m along the length of the hose from the edge of the lamp and appliance

⑤ the metal hose shall be reliably grounded and shall not be used as the grounding conductor of electrical equipment

(4) laying of plastic pipes

① the plastic pipes and their accessories used to protect wires must be made of flame-retardant materials, and the outer wall of the plastic pipes shall have connecting flame-retardant marks and manufacturer's logo with a spacing of no more than 1 m

② plastic pipes shall not be laid in places with high temperature and prone to mechanical damage

③ the plastic pipe orifice shall be flat and smooth; Tube to tube, tube to box (box) and other devices shall be connected by insertion method; The joint surface of the joint shall be coated with special adhesive. The interface shall be firmly sealed and meet the following requirements:

1) when the sleeve is used to connect the pipes, the length of the sleeve should be 1.5 ~ 3 times of the outer diameter of the pipe; The pipe to pipe butt joint shall be located in the center of the casing

2) when the tube is connected with the device, the insertion depth should be 1.1 ~ 1.8 times of the outer diameter of the tube

④ when hard plastic pipes are laid along the surface of buildings and structures, temperature compensation devices shall be installed according to the design regulations

⑤ where the exposed hard plastic pipe passes through the floor and is vulnerable to mechanical damage, it shall be protected by steel pipe, and the distance between the protection height and the floor surface shall not be less than 500 mm

⑥ for hard plastic pipes directly buried underground or in the floor slab, protective measures shall be taken where they are exposed to mechanical damage

⑦ the plastic pipe is directly buried in the cast-in-place concrete. When pouring concrete, measures shall be taken to prevent mechanical damage to the plastic pipe

⑧ the laying, installation and bending of plastic pipes and their accessories shall be carried out under the allowable ambient temperature specified for raw materials, and the temperature shall not be lower than -15 ℃

⑨ when the plastic pipe is laid in the groove on the brick wall, the cement mortar with strength grade not less than M10 shall be used for plastering protection, and the thickness of the protective layer shall not be less than 15mm

⑩ the exposed hard plastic pipes shall be arranged neatly, the spacing between fixed points shall be uniform, and the maximum distance between pipes shall comply with the provisions in Table 1. The distance between the pipe clamp and the terminal, turning midpoint, electrical appliance or box (box) edge is 150 ~ 500 mm

11 when laying semi-rigid plastic pipes or corrugated pipes, bending should be reduced. When the length of straight-line section exceeds 15m or there are more than three right angle bends, junction boxes should be added

2. Wiring of wires, cable conduits and trunking

(1) general provisions

① model and specification of wires used for wiring

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